The present invention relates to a part fabricating method and part fabricating apparatus for fabricating parts in the fields of metal industry, electronic industry, machinery industry and so on.
In the conventional part fabricating methods, there has been a method utilizing a machining technology or electric discharge technology to remove unwanted portions of objects to be machined into a desired shape to thereby fabricate parts. In the method utilizing a machining technology, parts have been fabricated using a cutting tool wherein any of the cutting tool and object to be machined is rotated to bring the cutting tool and the object to be machined into contact at the same time, thereby removing unwanted portions of the object to be machined into a desired shape. In the method utilizing an electric discharge technology, parts have been fabricated by making a machining electrode having a corresponding tip shape to a desired machining form wherein the machining electrode and the object to be machined are adjusted to a predetermined distance to repeatedly cause pulse-formed electric discharge between the machining electrode and the object to be machined, thus removing unnecessary portions of the object to be machined.
However, there have been some problems in the conventional part fabrication methods. First, the following points can be listed as the problems encountered in the machining technology.
(1) Because only removal machining is possible, there may be a case that the efficiency of material utilization is extremely worsened as the part fabricating shape may be, or a long machining time is required even for a simple shape.
(2) Because machinable shapes are limited to the type machining machine used, the fabrication of parts having complicated shapes requires many kinds of machining machines with increased process steps.
(3) Because operation is by contacting a cutting tool with an object to be machined, the consumption in the cutting tool is unavoidable. Because the consumption of the cutting tool raises a problem of lowering in machining accuracy or roughening in machining surface, the cutting tool must be exchanged as required and full automation for part fabrication is difficult.
(4) Because removal machining is effected by utilizing a physical force caused between a cutting tool and an object to be machined, there is affection due to the hardness or toughness of the object to be machined. Accordingly, there is a necessity of adjusting the type of cutting tool used and machining conditions in compliance with the material of the object to be machined.
(5) The machining resolution increases with decrease in tip diameter of a cutting tool, whereas there is limitation in cutting tool sharp-edging due to machining utilizing a physical force. Accordingly, there is difficulty in coping with miniaturization for fabrication parts.
Next, the following points can be listed as problems encountered in-the method utilizing the electric discharge technology.
(1) Because the forming shape of an object to be machined is determined by a tip shape of the machining electrode, before performing machining the machined electrode must have been previously made to have a tip shape corresponding to a desired forming shape.
(2) Because only removal of material from the object is possible similarly to the foregoing conventional machining process the efficiency of material utilization is decreased and a long machining time is required even for a simple shape.
(3) The consumption in the machining electrode is unavoidable similarly to machining, and the machining electrode has to be exchanged as required. In the electric discharge machining method, each exchange of the machining electrode, requires a machining electrode having a tip shape corresponding to a forming shape, thus worsening machining efficiency.
(4) Removal chips produced in machining adhere to a surface to be machined, having bad effects upon machining accuracy.
(5) In order to cause pulse-formed electric discharge required upon removal machining, a great voltage has to be applied, thus increasing energy consumption during machining.
(6) Because a machining electrode having a tip form corresponding to a desired part shape is utilized to effect removal from a surface to be machined, the direction of machining progression is only in a depth direction of the object to be machined and there is difficulty in fabricating parts having a complicated three-dimensional shape.
The present invention provides a means to solve the above-stated problems.
In order to solve the above-stated problems, the present invention is characterized by fabricating a part by: first performing removal machining on an object to be machined to fabricate a part cast mold, then depositing a metal A on a surface of the cast mold to form a metal A layer, depositing a metal B different in kind from the metal inside the cast mold to form a part, and finally selectively removing the metal A to take out the part.
Also, in a process of the cast mold fabrication, metal layer formation or part formation, the removal machining or metal deposition is effected by an electrolytic machining method wherein the object to be machined and a machining electrode are opposite placed in an electrolytic solution to cause electrochemical reaction for machining between a surface to be machined of the object to be machined and a tip of the machining electrode. Here, a sharp-edged electrode may be used as the machining electrode.
Also, in a process of the cast mold fabrication, metal layer formation or part formation, machining is made while moving the machining electrode or object to be machined along an arbitrary shape.
Also, a part fabricating apparatus is characterized by comprising: an object to be machined holding means for holding an object to be machined in an electrolytic solution, a machining electrode for subjecting machining in a surface to be machined of the object to be machined through electrochemical reaction, a spacing changing means for detecting and changing a spacing between the surface to be machined of the object to be machined held by the object to be machined holding means and the machining electrode, a potential/current control unit for controlling a potential/current on the machining electrode, an electrolytic solution changing means for arbitrary changing an electrolytic solution A for effecting removal machining on the surface to be machined to fabricate a cast mold, an electrolytic solution B for depositing a metal A on a surface of the cast mold to form the metal layer A, and an electrolytic solution C for depositing the metal B inside the cast mold to form a part.
The part fabricating apparatus is provided with the machining electrode, for example, sharp-edged, in order to increase machining accuracy.
Also, the part fabricating apparatus is provided, as a means to move the machining electrode and the object to be machined along an arbitrary shape in a process of the cast mold fabrication, metal layer formation or part formation, with a shape information memory means for memorizing arbitrary shape information and a moving position control means for moving the machining electrode or object to be machined along an arbitrary shape based on shape information memorized in the shape information memory means.
Also, the part fabricating apparatus is provided, as a means to use a plurality of machining electrodes, with a machining electrode holding means for holding the plurality of machining electrodes, and a machining electrode changing means for arbitrarily changing between the plurality of machining electrodes held by the machining electrode holding means.